Field of the Invention
The present disclosure relates to an organic light emitting display (OLED) device and a method of manufacturing the same, and more particularly, to an OLED device with reduced voltage drop in the cathode and improved aperture ratio.
Discussion of the Related Art
Organic light emitting display (OLED) devices are a self-luminous display that does not require an additional light source, different from liquid crystal display (LCD) devices. Therefore, OLED devices can be made lighter and thinner. Further, OLED devices have advantages in that they can be driven with low voltage and less power consumption, and that they represents vivid colors and have short response time, wide viewing angle and good contrast ratio (CR). For these reasons, OLED devices are currently under development as the next generation display.
In the case of a top-emission type OLED device, a transparent electrode or a semi-transmissive electrode can be used as a cathode in order to emit the light generated from an organic light emitting layer upward. In either case in which the transparent electrode or the semi-transmissive electrode is used as the cathode, the cathode has typically a small thickness in order to improve light transmittance. A decrease in thickness of the cathode increases the electric resistance of the cathode electrode. As a result, a large-area OLED device may suffer from a higher voltage drop, as the cathode is further from a voltage supply pad unit, that may cause luminance non-uniformity.
In order to minimize such a voltage drop, a method of forming a separate auxiliary electrode has been used. FIG. 1 is a schematic cross-sectional view of an OLED device that includes an auxiliary electrode according to the related art.
Referring to FIG. 1, an OLED device according to the related art includes a first auxiliary electrode 108, a second auxiliary electrode 107, a substrate 110, a buffer layer 120, a planarization layer 152, an anode 160, a bank layer 162, a partition 164, an organic layer 166, an organic light emitting layer 170, and a cathode 180.
Herein, the anode 160 and the first auxiliary electrode 107 are formed of the same material by the simultaneous process, and the organic light emitting layer 170 and the organic layer 166 are also formed of the same material by the simultaneous process. The second auxiliary electrode 108 is formed by using a separate process using a mask.
In the OLED device 100 of FIG. 1, the second auxiliary electrode 108 and the first auxiliary electrode 107, which are electrically connected with the cathode 180, is used to minimize the voltage drop to remedy the luminance non-uniformity problem of the OLED device.
However, in the OLED device 100 of FIG. 1, a sufficiently large area in each sub pixel region is desired to form the partition 164 and the first auxiliary electrode 107, which is disposed on the same layer and made of the same material as the anode 160. Because the area where the first auxiliary electrode 107 and the partition 164 are disposed typically does not contribute to the light emitting region, the aperture ratio of the OLED device 100 may be lowered.
Moreover, in order to maintain a uniform sheet resistance value, when the second auxiliary electrode 108 is disposed below the first auxiliary electrode 107 and above the planarization layer 152, a separate mask process may be required, as illustrated in FIG. 1. As a result, a manufacturing process of the OLED device 100 may become complicated, and a manufacturing time may increase.